Field
Example embodiments described herein relate generally to fan control arrangements for rack-mountable electronic equipment and, more particularly, to a profile switch that sets an operational profile for the control of a fan module.
Description of Related Art
Modular electronic equipment is typically arranged in chassis which are, in turn, installed in racks or cabinets. Generally, a telecommunications rack has vertical supports and is open on both sides, whereas a data center cabinet has sides and a back which are generally closed. Each rack or cabinet typically has an opening to receive the chassis. Such openings are typically one of a plurality of standard sizes, such as 23 inches, 19 inches, and 500 millimeters. Data center cabinets generally have a width of 19 inches, while telecommunications racks generally have a width of 23 inches.
One example of a representative chassis is each chassis 102 of the two rack-mountable-chassis (upper and lower) shown in FIG. 1, which is also shown as chassis 1800 in FIG. 1 of U.S. patent application Ser. No. 12/036,029.
The electronic components in the chassis generate heat which is typically removed by cooling fans in chassis. Such fans direct air across the electronic components to remove heat produced therefrom. For example, in one example aspect of the invention in the '029 application, the chassis is configured with forced air cooling provided by one or more fans, such as a fan (not shown) in a compartment 1826 of FIG. 1, and the like. The fan may be positioned and configured to provide forced air movement through the chassis 1800 in a direction from a second lateral surface 1806 to a first lateral surface 1814, or vice versa. The more open configuration of telecommunication racks provides less restriction to air flow, as compared to the closed cabinet configurations found in data centers, which can severely restrict air flow to the chassis. Also, the rack width itself can have an impact on air flow. In general, for a certain deployment environment, a rack having a larger opening will produce less restriction to airflow than a rack having a smaller opening. Further, various rack configurations for a given nominal rack opening width can have an impact on air flow. For example, racks having the same opening dimensions may be configured to meet different standards, such as the Electronic Industries Alliance (EIA) standard or the Seismic Unequal Flange Equipment Rack (SUFER) standard. In the latter case, the SUFER rack will be more restrictive to air flow than an EIA rack.
In addition to physical differences between racks and cabinets, the environment in which racks and cabinets (and the chassis therein) are employed typically differ as well. For example, cabinets are often deployed in data centers, while racks are often deployed in telecommunication offices. Different industry standards apply to environmental requirements for the various environments in which the chassis will operate.
Ambient temperature operational guidelines differ based on the operating environment for the chassis. For example, in a telecommunications office, Telcordia General Requirements Document Number 63 specifies a long and short term operational ambient temperature of 50 C and 40 C respectively. A data center environment conforming to Telcordia General Requirements Document Number 3160 accounts for a more restrictive deployment for chassis or cabinets and compensates with 10 C margin and defines the long term operational temperature of 30 C. Such temperatures represent the maximum temperature at the inlet to the chassis cooling system. Data centers are generally more thermally controlled compared to telecommunication offices. As such, equipment in data centers is not expected to operate at more extreme temperatures than those that may occur in telecommunication offices. Some equipment, like computer servers, is specifically intended for cabinet deployment in data centers and operates using front-to-rear forced cooling air flow. However, some telecommunications equipment is primarily intended for rack deployment in telecommunication offices and operate using side-to-side forced cooling air flow. When such telecommunications equipment is deployed in closed-sided data center cabinets having narrower widths than telecommunication racks, venting and thermal regulation can be more challenging than for rack deployment in telecommunication offices. For example, even though the threshold ambient temperatures are lower for data center environments, as a result of the closed construction of cabinets used to house chassis in data centers, the data center operating environment is considered to be more thermally challenging than that of the telecommunications office owing to airflow restrictions caused by the cabinets.
Also, with regard to acoustic level limits, Telcordia General Requirements Document Numbers 63 and 3160 define the acoustic emission of a product to be limited to 78 dBA for both the telecommunications office and the data center respectively. However, the same chassis and fan module combination will likely produce different sound volume levels when installed in a rack versus a cabinet.
Accordingly, it can be useful to provide a chassis deployed in an operating environment and constructed to take into account the operating environment, mounting configuration, and the number of chassis in the deployment. Furthermore, a system may consist of only one chassis, in which case each chassis has a higher acoustic emission limit.
One solution to complying with the varying thermal and acoustic requirements for the different operating environments that a chassis may encounter is to manufacture different chassis tailored to different operating environments. For example, a chassis has been manufactured which can receive differently constructed fan modules, each of which being constructed for a specific operating environment. However, producing assembled chassis with fan modules pre-installed based on the intended operating environment of the chassis, requires the manufacture of different fan modules to cover the gamut of various chassis configurations. Such a technique is costly.
Another approach to addressing chassis compliance with different operating environments has been to use software to configure the chassis and its component modules for their operating environments. The software is configured by the end user. However, such configurations, in some cases, may require the participation of the end user to deploy, manage, and update the software. Moreover, such configurations also may necessitate software support for older, legacy hardware, which can be costly.
Yet another approach is to operate the fans in such a way that risks violating the thermal or acoustic requirements discussed above. For example, the fans may be operated at their maximum speeds at all times, thereby possibly violating acoustic requirements. Operating continuously at full speed, however, will make power consumption significantly higher. There is a cubed law relationship between RPM percentage and power. For example, running fans at 70% maximum RPM consumes only 35% of the power compared to maximum. (0.7*0.7*0.7=0.34) Also, the fans can be operated at slower speeds all the time, but thereby risk not meeting thermal requirements for the chassis.